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Diazomethane

Diazomethane
Diazomethane
Diazomethane
Names
IUPAC name
Diazomethane
Other names
Azimethylene,
Azomethylene,
Diazirine
Identifiers
3D model (Jmol)
ChEBI
ChemSpider
ECHA InfoCard 100.005.803
KEGG
PubChem CID
Properties
CH2N2
Molar mass 42.04 g/mol
Appearance Yellow gas
Odor musty
Density 1.4 (air=1)
Melting point −145 °C (−229 °F; 128 K)
Boiling point −23 °C (−9 °F; 250 K)
hydrolysis
Structure
linear C=N=N
polar
Hazards
Main hazards toxic and explosive
R-phrases R12 R19 R22 R66 R67
S-phrases S9 S16 S29 S33
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g., fluorine Special hazards (white): no codeNFPA 704 four-colored diamond
Lethal dose or concentration (LD, LC):
175 ppm (cat, 10 min)
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 0.2 ppm (0.4 mg/m3)
REL (Recommended)
 TWA 0.2 ppm (0.4 mg/m3)
IDLH (Immediate danger)
 2 ppm
Related compounds
Related functional groups;
compounds
 R-N=N=N (azide),
R-N=N-R (azo);
R2CN2 R = Ph, tms, CF3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Diazomethane is the chemical compound CH2N2, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound. In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost universally used as a solution in diethyl ether. The compound is a popular methylating agent in the laboratory, but it is too hazardous to be employed on an industrial scale without special precautions.

For safety and convenience diazomethane is always prepared as needed as a solution in ether and used as such. It converts carboxylic acids into their methyl esters or into their homologues (see Arndt-Eistert synthesis). In the Büchner–Curtius–Schlotterbeck reaction diazomethane reacts with an aldehyde to form ketones.

When diazomethane is reacted with alcohols or phenols in presence of boron trifluoride (BF3), methyl ethers are obtained.

Diazomethane is also frequently used as a carbene source. It readily takes part in 1,3-dipolar cycloadditions.

Diazomethane is prepared by hydrolysis of an ethereal solution of an N-methyl nitrosamide with aqueous base. The traditional precursor is N-nitroso-N-methylurea, but this compound is itself somewhat unstable, and nowadays such compounds as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-methyl-N-nitroso-p-toluenesulfonamide (Diazald) are preferred.


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